linux-kernel - [PATCH v2 1/2] KVM: SVM: Allow KVM_SET_NESTED

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Message-ID: <20251009223153.3344555-2-jmattson@google.com>
Date: Thu,  9 Oct 2025 15:31:33 -0700
From: Jim Mattson <jmattson@...gle.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>, Sean Christopherson <seanjc@...gle.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Jim Mattson <jmattson@...gle.com>
Subject: [PATCH v2 1/2] KVM: SVM: Allow KVM_SET_NESTED_STATE to clear GIF when SVME==0

GIF==0 together with EFER.SVME==0 is a valid architectural
state. Don't return -EINVAL for KVM_SET_NESTED_STATE when this
combination is specified.

Fixes: cc440cdad5b7 ("KVM: nSVM: implement KVM_GET_NESTED_STATE and KVM_SET_NESTED_STATE")
Signed-off-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/svm/nested.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index a6443feab252..db0d4f2b128c 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1798,8 +1798,8 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 	 * EFER.SVME, but EFER.SVME still has to be 1 for VMRUN to succeed.
 	 */
 	if (!(vcpu->arch.efer & EFER_SVME)) {
-		/* GIF=1 and no guest mode are required if SVME=0.  */
-		if (kvm_state->flags != KVM_STATE_NESTED_GIF_SET)
+		/* GUEST_MODE must be clear when SVME==0 */
+		if (kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE)
 			return -EINVAL;
 	}
 
-- 
2.51.0.740.g6adb054d12-goog